Interplay Between Serum Apelin, Insulin Resistance and Body Mass Index in Patients with Non-Alcoholic Fatty Liver Disease: A Comparative Analysis

Abstract

Introduction: Non-alcoholic fatty liver disease (NAFLD) has become a leading cause of chronic liver disease, particularly among individuals with high BMI. Apelin, a bioactive peptide known for its involvement in metabolic processes, has emerged as a significant player in the pathogenesis of NAFLD. The present study explores the role of apelin in the development and progression of NAFLD in individuals with high body mass index (BMI), examining its potential as a biomarker. This study highlights the mechanisms through which apelin modulates insulin resistance (IR), lipid metabolism and development of NAFLD and to measure serum apelin and IR in patients with and without NAFLD and to investigate the correlation between these parameters and establish whether apelin can be used as a biomarker of NAFLD.

Materials and Methods: It was a cross-sectional study, conducted at the Post-graduate Dept. of Biochemistry in collaboration with the Dept. of General Medicine, SCB Medical College, Cuttack from October 2018 to September 2019. In this study, a total of 368 participants were included and grouped into four categories based on the degree of hepatic steatosis as assessed by ultrasound (USG) findings. Each of these groups have 92 participants. Group A (Grade 0 - Control) consisted of patients with a normal liver appearance, and these individuals served as the control group. Group B (Grade 1 - Mild NAFLD) included patients with mild hepatic steatosis, Group C (Grade 2 - Moderate NAFLD) comprised patients with moderate hepatic steatosis, Lastly, Group D (Grade 3 - Severe NAFLD) included patients with severe hepatic steatosis. All participants underwent evaluation of their biochemical profile which included Fasting Plasma Sugar (FBS), serum urea, creatinine, Total Cholesterol (TC), Triglyceride (TG), High-density Lipoprotein cholesterol (HDL-c), Low-density Lipoprotein cholesterol (LDL-c), Very Low-Density Lipoprotein (VLDL), serum apelin and serum insulin. The comparison between the groups was done by using the MANOVA test. The Chi-square test was used to compare categorical variables.

Results: The mean age of the study participants was 40.17+10.23 years. Among the study participants, 140 (38.0%) were females and 228 (62.0%) were males. The patients were grouped into four groups based on the NAFLD status. Serum apelin levels were substantially higher in Group D (263.14 ± 109.09 pg/mL) and Group C (205.57 ± 82.56 pg/mL) compared to Groups A and B, with a highly significant difference across all groups (p < 0.001). Serum insulin levels were significantly elevated in Group D (16.02 ± 8.01 mU/L) and Group C (15.41 ± 7.44 mU/L) compared to Groups A and B (p < 0.001). The HOMA-IR values followed a similar pattern, with Group D showing the highest insulin resistance (7.92 ± 2.44), and significant differences were observed across the groups (p < 0.001). There was significant positive correlation observed between serum apelin with BMI (r=0.367, p=0.003) and HOMA IR (r=0.742, p=0.001).

Conclusion:  The positive correlation between serum apelin levels in individuals with high BMI and Insulin resistance underscores the potential role of apelin in NAFLD pathophysiology